Compressor

ABSTRACT

A compressor is provided that may include a shell in which a discharge outlet may be provided; a cylinder provided inside of the shell and configured to form a compression space of a refrigerant; a piston provided inside of the cylinder and capable of reciprocating in an axial direction; and a discharge valve provided at one side of the cylinder and configured to selectively discharge a refrigerant compressed in the compression space of the refrigerant. The discharge valve may be formed with a magnesium (Mg) alloy in which the Mg has a weight ratio (wt %) of about 90 or higher, thus having a tensile strength of about 250 MPa or higher at about 150° C.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application claims priority under 35 U.S.C. §119 to Korean Application No. 10-2015-0094075, filed in Korea on Jul. 1, 2015, whose entire disclosure is hereby incorporated by reference.

BACKGROUND

1. Field

A compressor is disclosed herein.

2. Background

Generally, a compressor is a mechanical device that receives power from a power generation device, such as an electric motor or a turbine, in order to compress air, a refrigerant, or various other types of working gas and increase a pressure thereof. The compressor is widely being used in home appliances, such as a refrigerator and an air conditioner, and throughout the whole industry.

The compressor can be mainly classified as a reciprocating compressor that includes a compression space, into and from which a working gas, such as a refrigerant, is suctioned and discharged, formed between a piston and a cylinder, and compresses the working gas by the piston linearly reciprocating inside of the cylinder; a rotary compressor that includes a compression space, into and from which a working gas, such as a refrigerant, is suctioned and discharged, formed between an eccentrically-rotating roller and a cylinder, and compresses the working gas as the roller eccentrically rotates along an inner wall of the cylinder; and a scroll compressor that includes a compression space, into and from which a working gas, such as a refrigerant, is suctioned and discharged, formed between an orbiting scroll and a fixed scroll, and compresses a refrigerant as the orbiting scroll rotates along the fixed scroll. Of the reciprocating compressors, a linear compressor that allows a piston to be directly connected to a linearly-reciprocating drive motor, such that a compression efficiency may be improved without mechanical loss due to movement conversion, and configured with a simple structure, is being developed.

Generally, the linear compressor is configured such that a refrigerant is suctioned, compressed, and then discharged while a piston is linearly reciprocated in a cylinder by a linear motor inside of a closed shell. The linear motor is configured such that a permanent magnet is disposed between an inner stator and an outer stator, and the permanent magnet is driven to linearly reciprocate by a mutual electromagnetic force between the permanent magnet and the inner (or outer) stator. Also, as the permanent magnet is driven while being connected to the piston, the refrigerant is suctioned, compressed, and then discharged while the piston linearly reciprocates in the cylinder.

The linear compressor may further include a discharge valve selectively opened and closed in order to discharge the refrigerant compressed in a compression space in the cylinder. The discharge valve is movably disposed at one side of the cylinder and may be spaced apart from the cylinder and discharge a refrigerant when a refrigerant pressure in the cylinder becomes a set or predetermined pressure or higher. The discharge valve may be repeatedly opened and closed.

The performance of the discharge valve may be determined based on responsiveness. The responsiveness is a characteristic related to whether the discharge valve may be promptly opened and closed corresponding to a pressure change in the compression space.

In order to realize a rapid response of the discharge valve, the discharge valve may be formed with a material having a relatively small mass with respect to a predetermined volume, that is, a material having low density. For this, in the linear compressor according to the related art, a discharge valve formed with a plastic material is used.

However, when the discharge valve formed with a plastic material is used as the discharge valve, there is a problem in that a strength is lowered. More particularly, in a case of a discharge valve that acts with a cylinder in which a high-temperature environment is formed, there is a problem in that possibilities of wear and damages increase when the strength is low.

In relation to the linear compressor according to the related art, the present Applicant has filed an application, which has been registered as Korean Patent No. 10-0600767 issued Jul. 6, 2006 and entitled “Discharge Assembly of Linear Compressor”, which is hereby incorporated by reference.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments will be described in detail with reference to the following drawings in which like reference numerals refer to like elements, and wherein:

FIG. 1 is a cross-sectional view of a compressor according to an embodiment;

FIG. 2 is an enlarged view of “A” in FIG. 1;

FIG. 3 is an experimental graph showing that a wear amount of a discharge valve may be reduced when a coating layer of a set or predetermined material is formed at the discharge valve according to an embodiment;

FIG. 4 is a view illustrating a discharge valve assembly according to an embodiment;

FIG. 5 is a view illustrating a discharge valve assembly according to another embodiment; and

FIG. 6 is a view illustrating a discharge valve assembly according to another embodiment.

DETAILED DESCRIPTION

Hereinafter, embodiments will be described with reference to the accompanying drawings. However, embodiments are not limited to the embodiments described herein, and those of ordinary skill in the art will be able to easily suggest another embodiment within the scope.

FIG. 1 is a cross-sectional view of a compressor according to an embodiment. Referring to FIG. 1, a linear compressor 10 according an embodiment may include a cylinder 120 provided inside of a shell 100, a piston 130 that linearly reciprocates inside of the cylinder 120, and a motor assembly 170 that gives a driving force to the piston 130. The shell 100 may be configured by coupling of an upper shell and a lower shell, for example.

The shell 100 may include a suction unit or inlet 101, into which a refrigerant may be introduced, and a discharge unit or outlet 105, from which a refrigerant compressed inside of the cylinder 120 may be discharged. The refrigerant suctioned by the suction unit 101 may pass through a suction muffler 140 and flow into the piston 130. Noise may be attenuated during a process in which the refrigerant passes through the suction muffler 140.

A compression space P, in which a refrigerant may be compressed by the piston 130, may be formed inside of the cylinder 120. In addition, a suction hole 131 a, through which a refrigerant may be introduced into the compression space P, may be formed at the piston 130, and a suction valve 132 that selectively opens the suction hole 131 a may be provided at one side of the suction hole 131 a.

A discharge valve assembly (200, refer to FIG. 2) to discharge the refrigerant compressed in the compression space P may be provided at one side of the compression space P. That is, the compression space P may be understood as a space formed between one end portion of the piston 130 and the discharge valve assembly 200.

The discharge valve assembly 200 may include a discharge cover 220 that forms a discharge space of a refrigerant, a discharge valve 210 opened to introduce a refrigerant into the discharge space when a pressure of the compression space P becomes a discharge pressure or higher, and a valve spring 230 provided between the discharge valve 210 and the discharge cover 220 to give an elastic force in an axial direction. The term “axial direction” may refer to a direction in which the piston 130 reciprocates, that is, a horizontal direction in FIG. 1. The suction valve 132 may be formed at one or a first side of the compression space P, and the discharge valve 210 may be provided at the other or a second side of the compression space P, that is, the opposite side of the suction valve 132.

During a process in which the piston 130 linearly reciprocates inside of the cylinder 120, the suction valve 132 may be opened and the refrigerant may be suctioned into the compression space P when the pressure of the compression space P is lower than the discharge pressure and becomes a suction pressure or lower. On the other hand, when the pressure of the compression space P becomes the suction pressure or higher, the refrigerant in the compression space P may be compressed while the suction valve 132 is closed. When the pressure of the compression space P becomes the discharge pressure or higher, the valve spring 230 may be deformed to open the discharge valve 210, and the refrigerant may be discharged from the compression space P to be discharged to a discharge space of the discharge cover 220.

A refrigerant discharge hole (not illustrated) having a resonance chamber to reduce pulsation of a refrigerant discharged through the discharge valve 210 and configured to discharge the refrigerant may be formed at the discharge cover 220. The refrigerant in the discharge space may flow to a discharge muffler 107 through the refrigerant discharge hole and be introduced into a loop pipe 108. The discharge muffler 107 may reduce a flow noise of the compressed refrigerant, and the loop pipe 108 may guide the compressed refrigerant to the discharge unit 105. The loop pipe 108 may be coupled to the discharge muffler 107, extend toward an inner space of the shell 100, and be coupled to the discharge unit 105.

The linear compressor 10 may further include a frame 110. The frame 110 may fix the cylinder 120 and may be integrally configured with the cylinder 120 or fastened to the cylinder 120 by a separate fastening member. In addition, the discharge cover 220 and the discharge muffler 107 may be coupled to the frame 110.

The motor assembly 170 may include outer stators 171, 173, and 175 fixed to the frame 110 to be disposed or provided to surround the cylinder 120, an inner stator 177 disposed or provided to be spaced apart from the outer stators 171, 173, and 175 toward an inside thereof, and a permanent magnet 180 disposed or provided at a gap between the outer stators 171, 173, and 175, and the inner stator 177. The permanent magnet 180 may linearly reciprocate by a mutual electromagnetic force between the outer stators 171, 173, and 175 and the inner stator 177. The permanent magnet 180 may be formed with one magnet having one pole or formed by coupling a plurality of magnets having three poles.

The permanent magnet 180 may be coupled to the piston 130 by a connection member 138. The connection member 138 may extend toward the permanent magnet 180 from one end portion of the piston 130. As the permanent magnet 180 linearly moves, the piston 130 may linearly reciprocate in the axial direction together with the permanent magnet 180.

The outer stators 171, 173, and 175 may include coil winding bodies 173 and 175, and a stator core 171. The coil winding bodies 173 and 175 may include a bobbin 173, and a coil 175 wound in a circumferential direction of the bobbin 173. A cross-sectional surface of the coil 175 may have a polygonal shape, for example, a hexagonal shape. The stator core 171 may be configured by a plurality of laminations stacked in the circumferential direction and disposed or provided to surround the coil winding bodies 173 and 175.

When a current is applied to the motor assembly 170, a current flows in the coil 175, a flux is formed near the coil 175 due to the current flowing in the coil 175, and the flux flows while forming a closed circuit along the outer stators 171, 173, 175 and the inner stator 177. A force to move the permanent magnet 180 may be generated by an interaction between the flux flowing along the outer stators 171, 173, and 175 and the inner stator 177, and a flux of the permanent magnet 180.

A stator cover 185 may be provided at one side of the outer stators 171, 173, and 175. One or a first end of the outer stators 171, 173, and 175 may be supported by the frame 110, and the other or a second end thereof may be supported by the stator cover 185.

The inner stator 177 may be fixed to an outer circumference of the cylinder 120. In addition, the inner stator 177 may be configured by a plurality of laminations stacked in the circumferential direction at an outside of the cylinder 120.

The linear compressor 10 may further include a supporter 135 that supports the piston 130, and a back cover 115 that extends toward the suction unit 101 from the piston 130. The back cover 115 may be disposed or provided to cover at least a portion of the suction muffler 140.

The linear compressor 10 may include a plurality of springs 151 and 155 each having a natural frequency adjusted so that the piston 130 may resonate. The plurality of springs 151 and 155 may include a first spring 151 supported between the supporter 135 and the stator cover 185, and a second spring 155 supported between the supporter 135 and the back cover 115. A plurality of the first spring 151 may be provided at both sides of the cylinder 120 or the piston 130, and a plurality of the second spring 155 may be provided behind the cylinder 120 or the piston 130.

The term “forward direction” may refer to a direction from the suction unit 101 toward the discharge valve assembly 200. In addition, a direction from the piston 130 toward the suction unit 101 may be referred to as a “rearward direction”. In addition, the term “axial direction” may refer to a direction in which the piston 130 reciprocates, and the term “radial direction” may refer to a direction perpendicular to the axial direction. These definitions of the directions may be used identically also in the description below.

A predetermined oil may be stored in an inner bottom surface of the shell 100. An oil feed device 160 that pumps oil may be provided at a lower portion of the shell 100. The oil feed device 160 may be operated by vibration generated as the piston 130 linearly reciprocates and may pump oil upward.

The linear compressor 10 may further include an oil feed pipe 165 that guides a flow of oil from the oil feed device 160. The oil feed pipe 165 may extend from the oil feed device 160 up to a gap between the cylinder 120 and the piston 130. The oil pumped from the oil feed device 160 may pass through the oil feed pipe 165 to be fed to the gap between the cylinder 120 and the piston 130 in order to perform cooling and lubricating actions.

FIG. 2 is an enlarged view of “A” in FIG. 1. FIG. 3 is a graph showing that a wear amount of a discharge valve may be reduced when a coating layer of a set or predetermined material is formed at the discharge valve according to an embodiment.

Referring to FIG. 2, the discharge valve assembly 200 according to an embodiment may include the discharge valve 210 capable of selectively opening the compression space P in the cylinder 120. The discharge valve 210 may be installed to be supported by a front surface portion or front surface 121 of the cylinder 120.

The front surface portion 121 of the cylinder 120 may have a cylindrical or ring shape, which may be hollow. The refrigerant in the compression space P cannot be discharged while the discharge valve 210 is in contact with the front surface portion 121 of the cylinder 120, and the refrigerant in the compression space P may be discharged when the discharge valve 210 is spaced apart from the front surface portion 121.

The discharge valve 210 may include a valve main body 211 having a nearly or approximately disc shape. The valve main body 211 may include a rear surface portion or rear surface 211 a coming in contact with the front surface portion 121 of the cylinder 120 and extending in the radial direction, an inclined surface 211 b extending to be inclined forward so that a width thereof gradually narrows from the rear surface portion 211 a, a front surface portion 211 c extending in the radial direction from the inclined surface 211 b, and a protruding portion or protrusion 211 d that protrudes forward from the front surface portion 211 c to support the valve spring 230.

The front surface portion 211 c and the protruding portion 211 d may form a nearly “L” shape to form a support step that supports the valve spring 230. The support step may be referred to as a “spring coupling unit” or “spring coupler” which is coupled with the valve spring 230.

In addition, the valve main body 211 may include a valve recessed portion 212 recessed forward from the rear surface portion 211 a. The valve recessed portion 212 may be referred to as an “interference prevention groove” that prevents at least a portion of the piston 130 from interfering with the discharge valve 210 during a process in which the piston 130 is moved forward to compress the refrigerant. The at least a portion of the piston 130 may include a fastening member that fastens the suction valve 132 to the piston 130.

The discharge valve 210 may be formed of a magnesium (Mg) alloy that contains Mg as a main component. The weight ratios (wt %) of metal components forming the discharge valve 210 are shown in [Table 1] below.

TABLE 1 Metal Mg Y Nd Zr Zn Li Mn Cu Si Ni Weight 90~93 3.7~4.3 2.4~4.4 0.4~1.0 0.10~0.20 0.10~0.20 0.15~0.20 0.02~0.03 0.005~0.01 0.0010~0.0050 ratio (wt %)

More specifically, the discharge valve 210 may include Mg by about 90 to 93 wt %. The density of Mg may be formed to be relatively low. For example, the density of Mg may be formed to be approximately 30% or lower than a density of aluminum (Al). Consequently, Mg may be advantageous in terms of a performance preferentially required for a discharge valve, that is, responsiveness.

However, Mg itself may have a low strength. For example, Mg may have a lower strength than Al and may have a disadvantage of having a weak strength in a range of operating temperatures of the compressor, for example, a range within about 150° C. Consequently, in this embodiment, the discharge valve 210 may be formed of the Mg alloy instead of pure Mg. The Mg alloy may include a plurality of metal components other than Mg as strength-reinforcing substances.

The discharge valve 210 may include yttrium (Y) (atomic number 39) by about 3.7 to 4.3 wt % and neodymium (Nd) by about 2.4 to 4.4 wt %. As the atomic weights of Y and Nd are relatively large, in order to lower a density of the Mg alloy according to this embodiment, each of Y and Nd may be limited from having a weight ratio higher than a set or predetermined weight ratio. In this embodiment, through repeated experiments, the set weight ratio of each of Y and Nd has been determined as about 3.7 to 4.3 wt % and about 2.4 to 4.4 wt %. Y and Nd may particularly perform a function of reinforcing a strength of the discharge valve 210 which is operated in a high-temperature environment.

Other than the above, the discharge valve 210 may contain about 0.4 to 1.0 wt % of zirconium (Zr), about 0.10 to 0.20 wt % of zinc (Zn), about 0.10 to 0.20 wt % of lithium (Li), about 0.15 to 0.20 wt % of manganese (Mn), about 0.02 to 0.03 wt % of copper (Cu), about 0.005 to 0.01 wt % of silicon (Si), and about 0.001 to 0.005 wt % of nickel (Ni). The metals may be understood as components contained in order to reinforce the strength of the discharge valve 210.

In [Table 2] below, experimental results of performance of the discharge valve formed of the Mg alloy containing the plurality of metal components are shown.

TABLE 2 Tensile Strength Tensile Strength Density[g/cm³] [MPa, 25° C.] [MPa, 150° C.] Al Alloy 2.7 310 234 Mg Alloy 1.83 350 300 (Embodiment)

More specifically, [Table 2] shows a result of testing a tensile strength in a case of forming a discharge valve with an Al alloy (control group) and a case of forming the discharge valve with the Mg alloy according to this embodiment. The Al alloy may be understood as a general metal which is relatively light and has a high strength.

The density of the Mg alloy according to this embodiment is formed to be quite lower than the density of the Al alloy. That is, with respect to a predetermined volume, a mass of the Mg alloy is formed smaller than a mass of the Al alloy. Thus, it can be recognized that the Mg alloy is more advantageous in terms of responsiveness.

The tensile strength of the discharge valve may be understood as an important element in evaluating the performance of the discharge valve. More particularly, when the tensile strength of the discharge valve is not configured to be a set or predetermined strength or higher in a high-temperature environment, for example, an about 150° C. environment, corresponding to a temperature at a side of the discharge valve of the compressor, a wear amount of the discharge valve is relatively large, and thus, it is difficult to expect a required performance of the discharge valve. For example, the set strength may be about 250 MPa.

The tensile strength of the Mg alloy according to this embodiment may be formed higher than the tensile strength of the Al alloy. For example, in a room-temperature (about 25° C.) environment, the tensile strength of the Mg alloy (about 350 MPa) may be formed higher than the tensile strength of the Al alloy (about 310 MPa).

In addition, in a high-temperature (about 150° C.) environment, the tensile strength of the Mg alloy (about 300 MPa) may be formed higher than the tensile strength of the Al alloy (about 234 MPa). Although the tensile strength of the Mg alloy was configured to be higher than the set strength, the tensile strength of the Al alloy was configured to be lower than the set strength. In summary, it can be recognized that the discharge valve formed of the Mg alloy has a superior strength performance compared to a strength performance of the discharge valve formed of the Al alloy in the high-temperature environment and may satisfy the required set strength.

The discharge valve 210 may further include a coating portion or coating 213 disposed or provided at an outer surface of the valve main body 211. More particularly, the coating portion 213 may be disposed or provided at the rear surface portion 211 a of the valve main body 211.

As described above, the rear surface portion 211 a of the valve main body 211 is a portion repeatedly coming into contact with or attached closely to the cylinder 120 and may be understood as a portion prone to be worn or damaged. Consequently, the coating portion 213 may be disposed or provided at the rear surface portion 211 a, thereby improving a damping force or wear resistance of the discharge valve 210.

The coating portion 213 may be formed through treating a surface with components shown in [Table 3] below.

TABLE 3 Surface Treatment PTFE + Additive PTFE DLC Ceramic PEEK Surface 600~700 500 2,000 2,000 or 1,000 Hardness(Hv) higher Coating  30~100 30 1.5 10~150 10 Thickness(μm)

More specifically, the coating portion 213 may be formed by, for example, PTFE and additive components treated on a surface of the valve main body 211. PTFE is a fluoro-based polymer and is generally referred to as “Teflon”. The PTFE may improve a damping property of the discharge valve 210.

The additive may contain at least one of nano-diamond or a carbon nanotube. The nano-diamond may be understood as a stiffener capable of reinforcing wear resistance, and the carbon nanotube may be understood as a reinforcing agent that increases resistance on a transferred stress.

The PTFE and the additive may be mixed and sprayed onto the valve main body 211, thereby forming the coating portion 213. A surface hardness (Hv) of the coating portion 213 may be about 600 to 700 Hv based on a pencil hardness of about 3H, and a thickness thereof may be approximately 30 to 100 μm. The coating portion 213 has advantages of having a superior hardness and a small wear amount.

In another example, the coating portion 213 may include the PTFE. The PTFE may be applied on a surface of the valve main body 211 while a fluororesin is in a form of paint and form the coating portion 213 which is inert by going through heating and plastic deformation processes at a predetermined temperature.

The surface hardness (Hv) of the coating portion 213 formed of the PTFE may be about 500 Hv based on a pencil hardness of about 2H, and a thickness thereof may be approximately 30 μm. As the coating portion 213 has a low friction coefficient, when the coating portion 213 is coated on an outer surface of the valve main body 211, a lubricity of the surface may be enhanced and wear resistance may be improved.

In still another example, the coating portion 213 may include DLC. DLC is an amorphous carbon-based new material and may be understood as a substance in a shape of a thin film using carbon ions in a plasma or activated hydrocarbon molecules. The DLC may be disposed or provided at the valve main body 211 by surface treatment using physical vapor deposition (PVD).

The surface hardness (Hv) of the coating portion 213 formed of the DLC may be approximately 2,000 Hv, and a thickness thereof may be approximately 1.5 μm. Physical properties of the DLC are similar to those of diamond, and the DLC has a high hardness and wear resistance, a superior electrical insulation property, and a low friction coefficient, thus having superior lubricity.

In still another example, the coating portion 213 may include ceramic disposed or provided at the valve main body 211 by spray coating. The surface hardness (Hv) of the coating portion 213 formed of the ceramic may have a hardness of about 2,000 Hv or higher, and a thickness thereof may be approximately 10 to 150 μm.

In still another example, the coating portion 213 may include engineering plastic (polyetheretherketone (PEEK)). The engineering plastic may be disposed or provided at the valve main body 211 by being applied thereto. The surface hardness (Hv) of the coating portion 213 formed of the engineering plastic may be approximately 1,000 Hv, and a thickness thereof may be approximately 10 μm. The coating portion 213 has a superior impact resistance property.

The graph in FIG. 3 shows wear amount (μm) generated at the discharge valve 210 according to operating times of the discharge valve 210. The operating times of the discharge valve 210 may refer to a number of times in which the compression space P is opened and closed during operation of the compressor. That is, when the compression space P is opened and closed once, the operating times may be counted as one cycle.

The experiment was performed until 10⁷ cycles were repeated with respect to three cases related to the discharge valve 210. That is, the experiment was performed with respect to a case of not including the coating portion at the discharge valve 210, a case of forming the coating portion with a first material, and a case of forming the coating portion with a second material. The first material is “PTFE”, and the second material is “PTFE+additive”. In addition, as an experimental condition, an opened amount (distance) of the discharge valve 210 was set to about 1 mm, and an operating frequency of the compressor was set to about 50 Hz.

When the coating portion was not disposed or provided at the discharge valve 210, it can be recognized that the wear amount of the discharge valve 210 rapidly increased as the operating times increased. After 10⁷ cycles related to opening and closing the discharge valve 210 were repeated, a wear amount W1 was formed. For example, the W1 may be about 75 μm.

When the coating portion formed with the first material was disposed or provided at the discharge valve 210, the wear amount decreased compared to the case in which the coating portion was not disposed, but a wear amount W2 was still quite high. For example, the W2 may be about 20 μm.

When the coating portion formed with the second material was disposed or provided at the discharge valve 210, a wear amount W3 was relatively very small. For example, the W3 may be approximately 5 μm. The 5 μm may belong to a wear amount range having reliability in manufacturing a discharge valve. From the experiment, it can be recognized that the wear amount of the discharge valve 210 considerably decreases when the coating portion 213 is formed with “PTFE+additive”.

The discharge valve assembly 200 may further include the valve spring 230 that elastically supports the discharge valve 210. For example, the valve spring 230 may be a compression spring. In addition, the valve spring 230 may include a conical coil spring.

One or a first side portion or end of the valve spring 230 may be supported by the discharge valve 210, and the other or a second side portion or end thereof may be supported by the discharge cover 220. The discharge cover 220 may include a support step 222 that supports the other side portion of the valve spring 230. The support step 222 may extend from a surface of the discharge cover 220.

The one side portion of the valve spring 230 may be supported by “spring coupling units 211 c and 211 d” formed by the front surface portion 211 c and the protruding portion 211 d of the discharge valve 210. The spring coupling units 211 c and 211 d are prone to be worn or damaged as a stress is repeatedly acted thereon.

To prevent the wear or damage, the discharge valve 210 according to this embodiment may further include a sheet 215. The sheet 215 may include a sheet formed of the PTFE material, that is, a Teflon sheet. The sheet 215 may be disposed or provided at a portion or a surface on which the valve spring 230 repeatedly acts such that lubricity of the discharge valve 210 may be improved and an impact transferred from the valve spring 230 may be effectively absorbed.

FIG. 4 is a view illustrating a discharge valve assembly according to another embodiment. Referring to FIG. 4, a discharge valve assembly 300 according to this embodiment may include the discharge valve 210 that selectively opens and closes the compression space in the cylinder 120, and a spring 330 coupled to one side of the discharge valve 210. The spring 330 may include a coil spring.

The discharge valve 210 may include the front surface portion 211 c that forms the front surface and the protruding portion 211 d protruding forward from the front surface portion 211 c. The front surface portion 211 c and the protruding portion 211 d may form support steps 211 c and 211 d.

The spring 330 may include a spring main body 331, which may be twisted in a spiral shape. The spring main body 331 may include a surface-treated portion treated by barrel polishing, for example. The “barrel polishing” may be understood as a treatment method of removing protrusions and films remaining on a surface of the spring main body 331 by putting the spring main body 331 and an abrasive in a predetermined container and rotating or vibrating the container. The surface-treated portion, which is polished, may be disposed or provided at a surface of the spring main body 331, thereby reinforcing a strength of the spring.

One or a first side portion or end of the spring main body 331 may be supported by the support steps 211 c and 211 d. In addition, the one side portion of the spring main body 331 may include an end portion or end 333 spaced apart from the support steps 211 c and 211 d. That is, the end portion 333 may be disposed or provided by being bent in a direction of being spaced apart from the support steps 211 c and 211 d, more particularly the front surface portion 211 c. In other words, the front surface portion 211 c and the one side portion of the spring main body 331 including the end portion 333 may form a first set or predetermined angle 81.

The end portion 333 may form a relatively sharp surface (cut surface). During the process in which the discharge valve 210 is repeatedly opened and closed, when the end portion 333 applies a stress to the front surface portion 211 c, the front surface portion 211 c is prone to be damaged. Consequently, in this embodiment, at least a portion of the spring 330 may be configured to be bent in a direction of being spaced apart from the discharge valve 210, thereby preventing the discharge valve 210 from being damaged.

FIG. 5 is a view illustrating a discharge valve assembly according to another embodiment. Referring to FIG. 5, a discharge valve assembly 400 according to this embodiment may include a spring 430 formed in a cylindrical shape. The spring 430 may include a coil spring.

One or a first side portion or end of the spring 430 may be supported by the support step 222 of the discharge cover 220, and the other or a second side portion or end thereof may be supported by the support steps 211 c and 211 d of the discharge valve 210. The description related to the above may be referenced to the description of the previous embodiment. A cylindrical coil spring may be disposed or provided as the spring 430, thereby effectively guiding opening and closing actions of the discharge valve 210 in the axial direction.

FIG. 6 is a view illustrating a discharge valve assembly according to another embodiment. Referring to FIG. 6, a discharge valve assembly 500 according to this embodiment may include a spring 530 that provides a restorative force to the discharge valve 210. The spring 530 may include a plate spring.

One or a first side portion or end of the spring 530 may be supported by a discharge cover 520, and the other or a second side portion or end thereof may be supported by the discharge valve 210. More specifically, the spring 530 may be coupled to the protruding portion 211 d of the discharge valve 210.

A recessed portion 522 to prevent interference with the protruding portion 211 d during a process in which the discharge valve 210 operates may be formed at the discharge cover 520. The recessed portion 522 may be recessed forward from an inner surface of the discharge cover 520 and formed at a position corresponding to the protruding portion 211 d.

The discharge valve assembly 500 may further include spacers 540 to support both side portions of the spring 530. The spacers 540 may be interposed between both side portions of the spring 530 and inner surfaces of the discharge cover 520. The spacers 540 may be disposed or provided, thereby allowing the spring 530 and the inner surface of the discharge cover 520 to be spaced apart, and thus, securing a space for deformation of the spring 530.

A plate spring may be used as the spring 530, thereby having an advantage of preventing a phenomenon that may occur in a coil spring, that is, a rotation (on its axis) or torsion phenomenon of the spring, and a wear phenomenon of the discharge valve caused by the phenomenon.

According to embodiments disclosed herein, a discharge valve in which Mg is included as a main component is provided, thereby reducing a density of the discharge valve, and thus, having an advantage of improving responsiveness of the discharge valve. Predetermined metal components besides Mg may be included as much as set or predetermined weight ratios in the discharge valve, thereby reinforcing a strength thereto. More particularly, a strength performance in a high-temperature environment inside of a compressor may be improved.

In addition, a predetermined substance capable of improving a damping performance and wear resistance of the discharge valve may be coated on the discharge valve, thereby preventing a friction surface of the discharge valve from being worn or damaged during a process in which the discharge valve repeatedly opens and closes a compression space in a cylinder. Further, a surface of a spring that supports the discharge valve may be polished to reinforce a strength of the spring, thereby preventing wear of the spring during a process in which the discharge valve is operated.

A sheet may be mounted on a spring coupling unit of the discharge valve to which the spring is coupled, thereby preventing the discharge valve from being worn due to a force acting from the spring. One side portion or end of the spring disposed or provided at the spring coupling unit may extend to be inclined in a direction of being spaced apart from one point of the spring coupling unit or one surface of the discharge valve, thereby preventing the one side portion of the spring from strongly pressing one surface of the discharge valve. A plate spring may be used as the spring, thereby allowing a stress of the spring to evenly act on the discharge valve, and thus, preventing wear of the discharge valve.

Embodiments disclosed herein have been suggested to solve at least the problems mentioned above and is directed to providing a compressor having a discharge valve assembly with an improved performance.

Embodiments disclosed herein provide a compressor that may include a shell in which a discharge unit or inlet may be provided; a cylinder disposed or provided inside of the shell and configured to form a compression space of a refrigerant; a piston provided inside of the cylinder to be capable of reciprocating in an axial direction; and a discharge valve provided at one side of the cylinder and configured to selectively discharge a refrigerant compressed in the compression space of the refrigerant. The discharge valve may be formed with a magnesium alloy in which magnesium (Mg) has a weight ratio (wt %) of about 90 or higher, thus having a tensile strength of about 250 MPa or higher at about 150° C.

The discharge valve may include a valve main body that selectively opens the compression space in the cylinder, and a coating portion or coating disposed or provided at an outer surface of the valve main body to prevent wear of the discharge valve. In addition, the valve main body may include a rear surface portion or rear surface attached close to the cylinder, and the coating portion may be disposed or provided at the rear surface portion. The coating portion may include at least one of polytetrafluoroethylene (PTFE), diamond-like carbon (DLC), or ceramic. In addition, the coating portion may include PTFE and an additive to reinforce a strength thereof. The additive may include at least one of nano-diamond or a carbon nanotube.

The compressor may further include a valve spring that supports the discharge valve to provide a restorative force; a spring coupling unit disposed or provided at the discharge valve and to which the valve spring is coupled; and a sheet installed at the spring coupling unit in order to prevent wear of the discharge valve. The sheet may include a Teflon sheet. In addition, the valve spring may include a spring main body formed with a coil spring, and a surface-treated portion formed at the spring main body by polishing.

Also, the compressor may include a valve spring that supports the discharge valve to provide a restorative force; a spring coupling unit disposed or provided at the discharge valve and to which the valve spring is coupled; and an end portion provided at the valve spring and extending by being bent in a direction of being spaced apart from the spring coupling unit.

The compressor may further include a valve spring which supports the discharge valve to provide a restorative force, and the valve spring may include a conical coil spring or a cylindrical coil spring. The compressor may further include a valve spring that supports the discharge valve to provide a restorative force, and the valve spring may include a plate spring.

In addition, the Mg alloy may further include a metal to reinforce a strength of the discharge valve, and the metal may include at least one of yttrium (Y) or neodymium (Nd). The Mg alloy may include Y having about 3.7 to 4.3 wt %, and Nd having about 2.4 to 4.4 wt %.

Embodiments disclosed herein further provide a compressor that may include a shell in which a discharge unit may be provided; a cylinder disposed or provided inside of the shell and configured to form a compression space of a refrigerant; a frame that fixes the cylinder to the shell; a piston provided inside of the cylinder to be capable of reciprocating in an axial direction; a discharge valve configured to selectively open the compression space of the refrigerant and formed of an Mg alloy containing Mg, Y, and Nd each having a preset or predetermined weight ratio; and a valve spring that supports the discharge valve to provide a restorative force. The discharge valve may include a spring coupling unit, to which the valve spring may be coupled; a sheet installed at the spring coupling unit to reinforce a strength of the discharge valve; and a coating portion or coating disposed or provided at an outer surface of the discharge valve and formed of PTFE, nano-diamond, and a carbon nanotube.

In addition, the Mg alloy may include Mg having about 90 to 93 wt %; Y having about 3.7 to 4.3 wt %; and Nd having about 2.4 to 4.4 wt %. A surface hardness (Hv) of the coating portion may be about 600 to 700 Hv based on a pencil hardness of about 3H. The coating portion may be disposed or provided at the discharge valve by being sprayed thereon. The valve spring may include a conical coil spring, a cylindrical coil spring, or a plate spring.

Embodiments have been shown and described, but embodiments are not limited to the particular embodiments mentioned above. The embodiments may be modified in various ways by those of ordinary skill in the art to which the embodiments pertains without departing from the gist which is claimed in the claims below, and such modifications should not be understood as separate from the technical spirit or purview.

Any reference in this specification to “one embodiment,” “an embodiment,” “example embodiment,” etc., means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. The appearances of such phrases in various places in the specification are not necessarily all referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with any embodiment, it is submitted that it is within the purview of one skilled in the art to effect such feature, structure, or characteristic in connection with other ones of the embodiments.

Although embodiments have been described with reference to a number of illustrative embodiments thereof, it should be understood that numerous other modifications and embodiments can be devised by those skilled in the art that will fall within the spirit and scope of the principles of this disclosure. More particularly, various variations and modifications are possible in the component parts and/or arrangements of the subject combination arrangement within the scope of the disclosure, the drawings and the appended claims. In addition to variations and modifications in the component parts and/or arrangements, alternative uses will also be apparent to those skilled in the art. 

What is claimed is:
 1. A compressor, comprising: a shell in which a discharge outlet is provided; a cylinder provided inside of the shell and configured to form a compression space of a refrigerant; a piston provided inside of the cylinder and capable of reciprocating in an axial direction; and a discharge valve provided at one side of the cylinder and configured to selectively discharge a refrigerant compressed in the compression space of the refrigerant, wherein the discharge valve is formed with a magnesium (Mg) alloy in which the Mg has a weight ratio (wt %) of about 90 or higher, thus having a tensile strength of about 250 MPa or higher at about 150° C.
 2. The compressor of claim 1, wherein the discharge valve includes: a valve main body configured to selectively open the compression space in the cylinder; and a coating provided at an outer surface of the valve main body to prevent wear of the discharge valve.
 3. The compressor of claim 2, wherein the valve main body includes a rear surface provided adjacent to the cylinder, and wherein the coating is provided at the rear surface.
 4. The compressor of claim 2, wherein the coating includes at least one of polytetrafluoroethylene (PTFE), diamond-like carbon (DLC), or ceramic.
 5. The compressor of claim 2, wherein the coating includes PTFE and an additive to reinforce a strength thereof.
 6. The compressor of claim 5, wherein the additive includes at least one of nano-diamond or a carbon nanotube.
 7. The compressor of claim 1, further including: a valve spring configured to support the discharge valve to provide a restorative force; a spring coupler provided at the discharge valve and to which the valve spring is coupled; and a sheet installed at the spring coupler in order to prevent wear of the discharge valve.
 8. The compressor of claim 7, wherein the spring coupler includes at least one step provided on the discharge valve.
 9. The compressor of claim 7, wherein the sheet includes a Teflon sheet.
 10. The compressor of claim 7, wherein the valve spring includes: a spring main body including a coil spring; and a surface-treated portion formed at the spring main body by polishing.
 11. The compressor of claim 1, including: a valve spring configured to support the discharge valve to provide a restorative force; a spring coupler provided at the discharge valve and to which the valve spring is coupled; and an end portion provided at the valve spring and configured to extend by being bent in a direction of being spaced apart from the spring coupler.
 12. The compressor of claim 1, further including a valve spring configured to support the discharge valve to provide a restorative force, wherein the valve spring includes a conical coil spring, a cylindrical coil spring, or a plate spring.
 13. The compressor of claim 1, wherein the Mg alloy further includes a metal to reinforce a strength of the discharge valve, and the metal includes at least one of yttrium (Y) or neodymium (Nd).
 14. The compressor of claim 13, wherein the Mg alloy includes: Yttrium(Y) having about 3.7 to 4.3 wt %; and Neodymium(Nd) having about 2.4 to 4.4 wt %.
 15. A compressor, comprising: a shell in which a discharge outlet is provided; a cylinder provided inside of the shell and configured to form a compression space of a refrigerant; a frame configured to fix the cylinder to the shell; a piston provided inside of the cylinder and capable of reciprocating in an axial direction; a discharge valve configured to selectively open the compression space of the refrigerant and formed of a magnesium (Mg) alloy containing Mg, Yttrium(Y), and Neodymium(Nd) each having a predetermined weight ratio; and a valve spring configured to support the discharge valve to provide a restorative force, wherein the discharge valve includes: a spring coupler to which the valve spring is coupled; a sheet installed at the spring coupler to reinforce a strength of the discharge valve; and a coating provided at an outer surface of the discharge valve and formed of at least one of polytetrafluoroethylene (PTFE), nano-diamond, or a carbon nanotube.
 16. The compressor of claim 15, wherein the Mg alloy includes: Mg having about 90 to 93 wt %; Y having about 3.7 to 4.3 wt %; and Nd having about 2.4 to 4.4 wt %.
 17. The compressor of claim 15, wherein a surface hardness of the coating is about 600 to 700 Hv based on a pencil hardness of about 3H.
 18. The compressor of claim 15, wherein the coating is provided at the discharge valve by being sprayed thereon.
 19. The compressor of claim 15, wherein the valve spring includes a conical coil spring, a cylindrical coil spring, or a plate spring.
 20. A compressor, comprising: a shell in which a discharge outlet is provided; a cylinder provided inside of the shell and configured to form a compression space of a refrigerant; a piston provided inside of the cylinder and capable of reciprocating in an axial direction; a discharge valve provided at one side of the cylinder and configured to selectively discharge a refrigerant compressed in the compression space of the refrigerant, wherein the discharge valve is formed with a magnesium (Mg) alloy in which the Mg has a weight ratio (wt %) of about 90 or higher, and wherein the Mg alloy further includes a metal to reinforce a strength of the discharge valve, the metal including Yttrium(Y) having about 3.7 to 4.3 wt %; and Neodymium(Nd) having about 2.4 to 4.4 wt %. 